Node.h

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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
 
/*
    Dataquay
 
    A C++/Qt library for simple RDF datastore management.
    Copyright 2009-2012 Chris Cannam.
  
    Permission is hereby granted, free of charge, to any person
    obtaining a copy of this software and associated documentation
    files (the "Software"), to deal in the Software without
    restriction, including without limitation the rights to use, copy,
    modify, merge, publish, distribute, sublicense, and/or sell copies
    of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:
 
    The above copyright notice and this permission notice shall be
    included in all copies or substantial portions of the Software.
 
    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
    ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
    CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
    Except as contained in this notice, the name of Chris Cannam
    shall not be used in advertising or otherwise to promote the sale,
    use or other dealings in this Software without prior written
    authorization.
*/
 
#ifndef DATAQUAY_NODE_H
#define DATAQUAY_NODE_H
 
namespace Dataquay {
class Node;
}
 
// Declare this early, to avoid any problems with instantiation order
// arising from inclusion "races".  If this is not found when
// compiling, hoist this header so that it is included earlier than
// any other header that includes <QHash>
extern unsigned int qHash(const Dataquay::Node &);
 
#include "Uri.h"
 
#include <QString>
#include <QVariant>
 
class QDataStream;
class QTextStream;
 
namespace Dataquay
{
 
class Node
{
public:
    enum Type { Nothing, URI, Literal, Blank };
 
    Node() : type(Nothing), value() { }
 
    Node(Uri u) : type(URI), value(u.toString()) { }
 
    Node(QString v) : type(Literal), value(v) { }
 
    Node(QString v, Uri dt) : type(Literal), value(v), datatype(dt) { }
 
    Node(const Node &n) :
        type(n.type), value(n.value), datatype(n.datatype) {
    }
 
    Node &operator=(const Node &n) {
        type = n.type; value = n.value; datatype = n.datatype;
        return *this;
    }
 
    ~Node() { }
 
    static Node fromVariant(const QVariant &v);
 
    QVariant toVariant() const;
 
    QVariant toVariant(int metaTypeId) const;
 
    bool operator<(const Node &n) const {
        if (type != n.type) return type < n.type;
        if (value != n.value) return value < n.value;
        if (datatype != n.datatype) return datatype < n.datatype;
        return false;
    }
 
    struct VariantEncoder {
        virtual ~VariantEncoder() { }
        
        virtual QVariant toVariant(const QString &n) = 0;
 
        virtual QString fromVariant(const QVariant &v) = 0;
    };
 
    static void registerDatatype(Uri datatype,
                                 QString variantTypeName,
                                 VariantEncoder *encoder = 0);
 
    static Uri getDatatype(QString variantTypeName);
 
    static QString getVariantTypeName(Uri datatype);
    
    Type type;
    QString value;
    Uri datatype;
};
 
typedef QList<Node> Nodes;
 
bool operator==(const Node &a, const Node &b);
bool operator!=(const Node &a, const Node &b);
 
QDataStream &operator<<(QDataStream &out, const Node &);
QDataStream &operator>>(QDataStream &in, Node &);
 
std::ostream &operator<<(std::ostream &out, const Node &);
QTextStream &operator<<(QTextStream &out, const Node &);
 
}
 
#endif